VB.NET: DialogResult.No is not closing the form

Using Message Box DialogResult.No Condition for closing the form doesnot perform as expected.

The formclosing event aske user whether to save the document or not before closing.

The following is my FormClosing event.

    Private Sub PDFViewSimple_FormClosing(ByVal sender As Object, ByVal e As FormClosingEventArgs) _ 
Handles Me.FormClosing

            If doc.IsModified Then

                Dim message As String = "The document is modified, would you like to save it?"
                Dim caption As String = "File Not Saved"
                Dim buttons As MessageBoxButtons = MessageBoxButtons.YesNo
                Dim DefaultButton As MessageBoxDefaultButton = MessageBoxDefaultButton.Button1
                Dim icon As MessageBoxIcon = MessageBoxIcon.Question
                Dim result As DialogResult

                ' Displays A MessageBox.
                result = MessageBox.Show(message, caption, buttons, icon, DefaultButton)

                If (result = DialogResult.Yes) Then
                    Me.Save(Me.Text)
                    Me.Close()
                ElseIf (result = DialogResult.No) Then
                    Me.Close()  ''Should I replace with (Application.Exit)
                End If

            End If

    End Sub

Solution

There's all sorts wrong with that code. Firstly, given that there are only two options, using ElseIf is pointless, although not strictly wrong. If it's not Yes then it must be No, so you'd only need an Else:

If (result = DialogResult.Yes) Then
    Me.Save(Me.Text)
    Me.Close()
Else
    Me.Close()
End If

Next, even an Else is pointless because you're calling Close regardless of the outcome. All you need to do is check for Yes, do anything specific to Yes and then call Close regardless:

If (result = DialogResult.Yes) Then
    Me.Save(Me.Text)
End If

Me.Close()

Finally, you shouldn't be calling Close at all. You're in the FormClosing event handler so the form is already closing. You only have to do something if you want the form to NOT close. So, all you need is this:

If (result = DialogResult.Yes) Then
    Me.Save(Me.Text)
End If

If you wanted the form to NOT close then you would set e.Cancel to True.